The present invention relates to welding masks or shields and more specifically to a novel mounting arrangement for the filter which effectively blocks the entrance of external harmful light rays to the interior of the mask to provide an effective shield against ultra-violet, visible and infrared radiation from a welding arc and thereby to protect the user against harmful radiation.
The general construction and arrangement of welding masks or shields are not new per se. Typical prior art welding masks or shields are shown in various prior United States patents including the following: R. Malcolm No. 1,904,933 issued Apr. 25, 1933; N. Anderson No. 3,257,667 issued Jan. 28, 1966; and J. N. Simpson et al No. 3,458,865 issued Aug. 5, 1969. These prior art masks are generally of similar construction and comprise a shield section preferably curved to conform somewhat to the face of the wearer which extends upwardly and rearwardly. The shield section is preferably molded as a unit from an opaque, plastic, lightweight, stiff material. The shield is normally worn on the head of the user and includes some type of head band so that it may be pivoted upwardly when not in use and easily moved to a face protecting position. When in a face protecting position, the shield is spaced forwardly of the wearer's face and extends around the side of the wearer's heaad so as to cover the head. The shield is usually provided with an enlarged rectangular opening within which is mounted a lens assembly consisting of a plurality of panes including, for example, an outer pane formed of a transparent material such as glass, an inner pane formed of similar material but which is tinted or colored so as to eliminate the transmission of harmful radiation to the eyes of the wearer which may be produced when contact is made between an energized welding rod and a work piece. The panes are usually separated by a gasket and are of a peripheral dimension conforming generally to the shape of the pocket-like viewing port in the shield but slightly undersized so that they may be easily assembled therein. The panes are usually supported in the rectangular opening by means of a spring clip. It has been found, however, that by reason of the fact that the panes do not snugly fit in the frame and the spring clip does not shield the peripheral gap between the lens stack and viewing port in the shield, there is light leakage, for example, past the filter as illustrated schematically in FIG. 1a producing a corona or halo effect which is distracting to the user and may even be harmful. Thus even where the filter plates conform with the radiant-energy transmittance requirements of the American National Standard for Occupational and Educational Eye and Face Protection, there is still the danger of light leakage past the filter which can be harmful to the user.
With the foregoing in mind, an object of the present invention is to provide a novel mounting means for the lens assembly for a shield or mask which effectively blocks penetration of harmful rays to the interior of the mask when it is in a face shielding position. This is accomplished by a mounting assembly which is of a relatively simplified construction so that the overall manufacturing costs of the entire assembly including the parts and assembling the parts together is economical and in accordance with one embodiment wherein the function of the insert and spring clip are integrated in a unitary piece is less than the cost of prior art assemblies of the type discussed above.